Eucalyptus Essential Oil

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Eucalyptus Essential Oil – General Description

Eucalyptus essential oil is one of the world’s most popular and widely-used essential oils. It is produced via steam distillation from the leaves of plants belonging to the genus Eucalyptus and can be broadly categorized as either medicinal, perfumery, or industrial in terms of use. ^[1] It is said to offer a “cleansing, invigorating, balancing, cheering, and purifying” feel and has a cooling and deodorizing effect on the body. ^[2] Eucalyptus essential oil appears clear to pale yellow in appearance with a thin consistency ^[3] and is widely favored for its distinct, clear, sharp, herbaceous aroma with soft woody undertones. ^[2]

Although the leaves of Eucalyptus globulus (Labill) are the world’s main source of eucalyptus essential oil because of the superior antiseptic and antimicrobial activity of this species in comparison to others, other varieties have been utilized as well, namely, E. radiata (Sieber ex DC) and E. citriodora (Hook). Mulyaningsih, Sporer, Reichling, and Wink (2011) had reported that the eucalyptus essential oil derived from the fruits of E. globulus is greater in activity than the leaf essential oils of E. globulus, E. radiata Sieber ex DC, and E. citriodora Hook against multidrug-resistant bacteria. ^[4] E. globulus is one of seven euaclypts that grow to over 80 metres (262 ft), making it one of the world’s tallest trees.

Eucalyptus Essential Oil – Uses and Reported Benefits

Eucalyptus essential oil has been exploited worldwide for fragrance purposes in whole form in soaps, perfumes, and disinfectants.

Through fractionation of the crude essential oil, the citronellal acquired can be utilized for aromas or can be converted to other derivatives intended for perfumery. ^[1]

Eucalyptus essential oil can come in a wide variety of pharmacological forms and preparations, from inhalant or chest rub to alleviate breathing difficulties, to mouthwash in water to refresh the throat, to skin rub to relieve aches and pains, to anti-plaque solutions for dental hygiene. ^[1] In Brazilian folk medicine, eucalyptus is used to remedy cold, flu, fever, and bronchial infections. ^[5] The majority of the putative medical uses of eucalyptus essential oil consist of being (1) an aid to fevers, migraines, and malaria; (2) a pain relief measure in cases of muscle aches, headaches, or sprains; and (3) a soothing agent (diluted oil taken by mouth) for respiratory system ailments such as coughs, asthma, throat infections, sinusitis, and catarrhal conditions. ^[2] Also, the oil is often applied as a home remedy to alleviate, soothe, and/or treat minor burns, blisters, wounds, insect bites, lice, skin infections, sore muscles and joints. ^[3]

Eucalyptus Essential Oil – Contraindications and Safety

Eucalyptus essential oil should not be taken internally or applied on skin at full strength. It should be used diluted, especially for any application other than aromatherapy, for safety. ^[6] Luckily, it works well with a variety of other essential oils such as basil, cajeput, cedarwood, citronella, ginger, lavender, lemon, myrtle, frankincense, spearmint, and tea tree. ^[3] For suggested dilution ratios, one should seek professional reference source or essential oil books.

Patients or individuals with high blood pressure or epilepsy are advised to avoid eucalyptus essential oil. ^[3] Furthermore, pregnant and lactating women are referred to a practitioner prior to use as not much has been scientifically explored as regards the safety of eucalyptus essential oil during pregnancy or breast-feeding. ^[7]

As detailed earlier, eucalyptus essential oil should only be taken in diluted form. Stomach pain and burning, dizziness, muscle weakness, and feelings of suffocation are likely to result from any overdose or poisoning with eucalyptus oil. ^[7] An intake of 3.5 mL of undiluted eucalyptus essential oil proves to be life threatening, causing delirium, convulsions, CNS depression (including coma), and eventually death. ^[8]

Eucalyptus Essential Oil – Scientific Studies And Research

A good pool of data has demonstrated the antiseptic properties of eucalyptus essential oil against a wide range of microbial agents. The leaf extract from E. globulus had been reported to be active against 56 isolates of Staphylococcus aureus, 25 isolates of Streptococcus pyogenes, 12 isolates of Streptococcus pneumoniae, and 7 isolates of Haemophilus influenzae, all of which were acquired from 200 clinical specimens of patients with respiratory tract disorders in the study of Salari, Amine, Shirazi, Hafezi, and Mohammadypour (2006). ^[9]

Schnitzler, Schön, and Reichling (2001) provided scientific support on the antiviral action of eucalyptus essential oil against herpes simplex virus (HSV) (50% inhibitory concentration (IC50) of 0.009% and 0.008% for HSV-1 and HSV-2, respectively). In this study, eucalyptus essential oil affected the virus before or during adsorption but not after the penetration into the host cell. ^[10]

Eucalyptus essential oil helps patients with diseases of inflammatory pathology. It does this by suppressing the production of nitric oxide (NO) via its NO scavenging activity and/or inhibitory effects on iNOS gene expression. ^[11] A Chinese study had found favorable effects from eucalyptus essential oil use on the inflammation known to occur in chronic bronchitis and on mucin hypersecretion in rat models. In the said study, chronic bronchitis was established in rats by instilling 0.2 mg of lipopolysaccharide, and pathologic manifestations were screened post 3 weeks. Results from this study detailed that the administration of eucalyptus essential oil significantly reduced not only the inflammatory cell infiltration and bronchiolitis severity in rats but also the mucin content in the trachea and bronchiole epithelium. ^[12] Eucalyptus essential oil diminishes airway hypersecretion, which results from an increased release of inflammatory mediators, through the action of its eucalyptol. Eucalyptol, or 1,8-cineole, is a natural compound in eucalyptus essential oil known to suppress arachidonic acid metabolism and cytokine production in human monocytes. The anti-inflammatory effects of eucalyptol prove to be of benefit to conditions such as asthma where eucalyptus essential oil can be used as a mucolytic agent in upper and lower airway diseases. ^[13]

Aside from being an anti-inflammatory agent, eucalyptus essential oil also possesses analgesic properties. Initial observations by Silva et al. (2003) offered evidence on the central and peripheral analgesic effects of the essential oils derived from E. citriodora, E. tereticornis, and E. globulus in addition to their neutrophil-dependent and neutrophil-independent anti-inflammatory activities. ^[5]

Administration of eucalyptus essential oil can also enhance one’s immunity by positively affecting the monocyte–macrophage system. The said system is one of the primary cellular effectors of the immune response against pathogens and warrants the detection and elimination of foreign bodies. Eucalyptus essential oil stimulates the activation of monocyte-derived macrophages and appears to function via complement receptor–mediated phagocytosis. ^[14]

Eucalyptus Essential Oil – Molecular Components and Chemistry

In the study of Ait-Ouazzou et al. (2011), 1,8-cineole (79.85%) was found as the major component in E. globulus essential oil. The results of this study had demonstrated the bacteriostatic and bactericidal action of E. globulus essential oil against seven pathogenic and spoiling bacteria. ^[15] 1,8-Cineole being a major component of E. globulus is a finding similar to that of Maciel et al. (2010); in addition, Z-citral and alpha-citral were also isolated from E. staigeriana and citronellal from E. citriodora. ^[16] Examining the essential oils from the dried leaves of thirteen Eucalyptus species, Elaissi et al. (2010) identified the following at varying contents from the different species analyzed (81.5 to 98.9% of the total oil):

1,8-Cineole
Cryptone
Spathulenol
p-Cymene
Viridiflorol
Globulol
Beta-eudesmol
Alpha-terpineol
Limonene
D-piperitone
Alpha-pinene
Cuminal
Gamma-eudesmol ^[17]